In the process of oil production, if the supply of fluid from the low-yield wells is insufficient, the theoretical displacement of a single well needs to be reduced. Since the work mode of the conventional operations of the walking beam oil pumping unit is limited to a continuous complete-cycle motion of the crank, the theoretical displacement of the single well can only be reduced by reducing the working strokes in the whole process or using the interval pumping work mode. However, the reduction of strokes in the whole cycle will cause the problem that the leakage rate of the plunger pump gradually increases, and the driving efficiency of the motor will gradually decrease as the motor speed decreases. Moreover, the use of interval pumping work mode will waste a large amount of manpower, material resources, and financial resources.
Regarding the technical requirements for reducing the theoretical displacement of a single well, and in order to overcome the technical problems caused by reducing the working strokes in the whole process and using the interval pumping work mode, both of the Patent application No. 201510783876.2, entitled “No-pumping/swabbing Operation Method for Walking Beam Pumping Unit Based on Crank incomplete-Cycle Motion” and the Patent application No. 201510838831.0, entitled “Dynamic Variable Stroke Operation Method For Walking Beam Pumping Unit Based on Crank Incomplete-cycle Motion” break through the technical bias that the walking beam pumping unit only has one operation mode, i.e., the crank continuous complete-cycle motion. With the incomplete-cycle swing motion of the crank, a no-pumping/swabbing or pumping/swabbing operation without the need of shutting down can be realized. If the traditional crank continuous complete-cycle motion is combined with the crank incomplete-cycle motion proposed by the two patents mentioned above, the theoretical displacement of a single well can be reasonably reduced. Meanwhile, the problems of large plunger leakage rate and reduced motor chive efficiency in the working strokes of the whole process can be solved, and the problem that the interval work mode causes waste of manpower, material resources, and financial resources can also be solved.
Based on the above-mentioned ideas, in the patent application No. 201610326037.2 entitled “Combined Operating Method for the Work Mode of Walking Beam Pumping Unit”, the crank complete-cycle operation, the crank incomplete-cycle pumping/swabbing operation, and the crank incomplete-cycle no-pumping/swabbing operation are combined, and the combination scheme of the three work modes are provided. Namely, the scheme of how to allocate the parameters (e.g. the number of times, time of duration, etc.) of the three work modes according to the number of theoretical full-stroke pumping/swabbing in a cycle.
In order to break through the technology biases that the walking beam pumping unit only has one operation mode, i.e. the crank continuous complete-cycle motion, and to combine the crank complete-cycle operation, the crank incomplete-cycle pumping/swabbing operation, and the crank incomplete-cycle no-pumping/swabbing operation, the conventional driving mode of the motor used to drive the crank needs to be changed to support the above mentioned aspects. However, neither the patent application No. 201510783876.2 entitled “No-pumping/swabbing Operation Method for Walking Beam Pumping Unit Based on Crank Incomplete-Cycle Motion” and the patent application No. 201510838831.0 “Dynamic Variable Stroke Operation Method For Walking Beam Pumping Unit Based on Crank Incomplete-cycle Motion”, nor the patent application No. 201610326037.2 entitled “Combined Operating Method for the Work Mode of the Walking Beam Pumping Unit” disclose how to combine the crank complete-cycle operation, the incomplete-cycle pumping/swabbing operation, and the incomplete-cycle no-pumping/swabbing operation and the driving means of the electric machine under such non-conventional work mode.